United States

 The United States of America (commonly called the United States, the U.S., the USA, America, and the States) is a federal constitutional republic consisting of fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states and Washington, D.C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to the east and Russia to the west across the Bering Strait. The state of Hawaii is an archipelago in the mid-Pacific. The country also possesses several territories in the Pacific and Caribbean. At 3.79 million square miles (9.83 million km2) and with over 314 million people, the United States is the third- or fourth-largest country by total area, and the third-largest by both land area and population. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries.[6]

Paleoindians migrated from Asia to what is now the United States mainland around 15,000 years ago. The descendent and isolated Native American population was greatly reduced by European contact, primarily by disease brought by explorers and traders. European colonization occurred, beginning about 1600, chiefly from England. The United States emerged from thirteen British colonies located along the Atlantic seaboard, which developed their own economies and democratic political systems. Patriots protested at British intrusions into taxation policies that Americans considered their rights, leading to war in 1775. On July 4, 1776, delegates from the 13 states to the Continental Congress unanimously issued the Declaration of Independence, which established the United States of America. The new nation, in alliance with France, defeated Britain, along with its Amerindian allies and German mercenaries, in the American Revolution.[7] It was the first successful war of independence against a European empire.[8] The current United States Constitution was adopted on September 17, 1787; its ratification the following year made the states part of a single republic with a stronger central government. The Bill of Rights, consisting of ten constitutional amendments guaranteeing many fundamental civil rights and freedoms, was ratified in 1791.

A "second war of independence" in the War of 1812 secured U.S. claims against the British Empire and guaranteed Canadian territorial integrity. The United States embarked on a vigorous expansion across North America throughout the 19th century. It displaced native tribes, acquiring the Louisiana territory from France and Florida from Spain; annexed the Republic of Texas in 1845, leading to war in which it conquered a large area of Mexico; and purchased Alaska from Russia in 1867. During the early territorial expansion, significant disputes between the agrarian slave-holding South and industrial North led to the American Civil War. The North's victory reestablished the Union, leading to the ratification of the Thirteenth Amendment to the United States Constitution and ending legalized slavery in the United States. The Plains Indian Wars relocated remaining tribes onto confined reservations, a Congressional Resolution annexed the Republic of Hawaii, then the treaty ending the Spanish–American War ceded Puerto Rico, Guam, as well as the Philippines (which later became independent). By the end of the nineteenth century, the American national economy was the world's largest.[9]

The Spanish–American War and World War I confirmed the country's status as a global military power. The United States emerged from World War II as the first country with nuclear weapons and a permanent member of the United Nations Security Council. The end of the Cold War and the dissolution of the Soviet Union left the United States as the sole superpower. The U.S. economy is the world's largest national economy, with an estimated 2011 GDP of $15.1 trillion (22% of nominal global GDP and over 19% of global GDP at purchasing-power parity).[3] [10] Per capita income is the world's sixth-highest.[3] The country accounts for 41% of global military spending,[11] and is a leading economic, political, and cultural force in the world.[12] [13] {| class="toc" id="toc"

Contents

 * 1 Etymology
 * 2 History
 * 2.1 Native American and European settlement
 * 2.2 Independence and expansion
 * 2.3 Slavery, civil war and industrialization
 * 2.4 World War I, Great Depression, and World War II
 * 2.5 Cold War and protest politics
 * 2.6 Contemporary era
 * 3 Government and politics
 * 3.1 Parties and ideology
 * 4 Foreign relations and military
 * 5 Economy
 * 6 Geography and environment
 * 7 Political divisions
 * 7.1 Income and human development
 * 8 Infrastructure
 * 8.1 Science and technology
 * 8.2 Transportation
 * 8.3 Energy
 * 8.4 Education
 * 8.5 Health
 * 9 Crime and law enforcement
 * 10 Demographics
 * 10.1 Language
 * 10.2 Religion
 * 10.3 Family structure
 * 11 Culture
 * 11.1 Popular media
 * 11.2 Literature, philosophy, and the arts
 * 11.3 Food
 * 11.4 Sports
 * 11.5 Measurement systems
 * 12 See also
 * 13 References
 * 14 External links
 * }

Etymology
See also: Names for United States citizensIn 1507, German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere "America" after Italian explorer and cartographer Amerigo Vespucci.[14]

The first documentary evidence of the phrase "United States of America" was in an anonymously written essay published in the Virginia Gazette newspaper in Williamsburg, Virginia on April 6, 1776.[15] [16] In June 1776, Thomas Jefferson included the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence.[17] [18] In the final Fourth of July version of the Declaration, the pertinent section of the title was changed to read, "The unanimous Declaration of the thirteen united States of America".[19]

On November 15, 1777, the Second Continental Congress adopted the Articles of Confederation, which states, "The Stile of this Confederacy shall be 'The United States of America'". The Franco-American treaties of 1778 used "United States of North America", but from July 11, 1778, "United States of America" was used on the country's bills of exchange, and it has been the official name ever since.<sup class="reference" id="cite_ref-20">[20]

The short form "United States" is also standard. Other common forms include the "U.S.", the "USA", and "America". Colloquial names include the "U.S. of A." and, internationally, the "States". "Columbia", a name popular in poetry and songs of the late 1700s,<sup class="reference" id="cite_ref-21">[21] derives its origin from Christopher Columbus; it appears in the name "District of Columbia".

The standard way to refer to a citizen of the United States is as an "American". "United States", "American" and "U.S." are used to refer to the country adjectivally ("American values", "U.S. forces"). "American" is rarely used in English to refer to subjects not connected with the United States.<sup class="reference" id="cite_ref-22">[22]

The phrase "United States" was originally treated as plural—e.g., "the United States are"—including in the Thirteenth Amendment to the United States Constitution, ratified in 1865. It became common to treat it as singular—e.g., "the United States is"—after the end of the Civil War. The singular form is now standard; the plural form is retained in the idiom "these United States".<sup class="reference" id="cite_ref-23">[23]

History
Main article: History of the United States===Native American and European settlement=== The indigenous peoples of the U.S. mainland, including Alaska Natives, are believed to have migrated from Asia, beginning between 40,000 and 12,000 years ago.<sup class="reference" id="cite_ref-24">[24] Some, such as the pre-Columbian Mississippian culture, developed advanced agriculture, grand architecture, and state-level societies. After Europeans began settling the Americas, many millions of indigenous Americans died from epidemics of imported diseases such as smallpox.<sup class="reference" id="cite_ref-25">[25] The whole of what is today described as the "U.S. mainland" was once the land of the indigenous peoples.<sup class="reference" id="cite_ref-26">[26] In 1492, while under contract to Spanish crown, Genoese explorer Christopher Columbus discovered several Caribbean islands and made first contact with the indigenous people.<sup class="reference" id="cite_ref-Hounshell1984_27-0">[27] On April 2, 1513, Spanish conquistador Juan Ponce de León landed on what he called "La Florida" - the first documented European arrival on what would become the U.S. mainland.<sup class="reference" id="cite_ref-Miller1998_28-0">[28] Spanish settlements in the region were followed by ones in the present-day southwestern United States. French fur traders established outposts of New France around the Great Lakes; France eventually claimed much of the North American interior, down to the Gulf of Mexico.<sup class="reference" id="cite_ref-White2012_29-0">[29]

The first successful English settlements were the Virginia Colony in Jamestown in 1607 and the Pilgrims' Plymouth Colony in 1620.<sup class="reference" id="cite_ref-Graddol1996_30-0">[30] The 1628 chartering of the Massachusetts Bay Colony resulted in a wave of migration; by 1634, New England had been settled by some 10,000 Puritans. Between the late 1610s and the American Revolution, about 50,000 convicts were shipped to Britain's American colonies.<sup class="reference" id="cite_ref-31">[31] Beginning in 1614, the Dutch settled along the Hudson River, including New Amsterdam on Manhattan Island, and Fort Nassau, present day Albany.<sup class="reference" id="cite_ref-Reps1992_32-0">[32]

In 1674, the Dutch ceded their American territory to England; the province of New Netherland was renamed New York.<sup class="reference" id="cite_ref-NortonSheriff2008_33-0">[33] Many new immigrants, especially to the South, were indentured servants—some two-thirds of all Virginia immigrants between 1630 and 1680.<sup class="reference" id="cite_ref-34">[34] By the turn of the 18th century, African slaves were becoming the primary source of bonded labor in many regions.<sup class="reference" id="cite_ref-Quirk2011_35-0">[35]

With the 1729 division of the Carolinas and the 1732 colonization of Georgia, the thirteen British colonies that would become the United States of America were established.<sup class="reference" id="cite_ref-BilhartzElliott2007_36-0">[36] All had local governments with elections open to most free men, with a growing devotion to the ancient rights of Englishmen and a sense of self-government stimulating support for republicanism. All legalized the African slave trade.<sup class="reference" id="cite_ref-Wood1998_37-0">[37] With high birth rates, low death rates, and steady immigration, the colonial population grew rapidly. The Christian revivalist movement of the 1730s and 1740s known as the Great Awakening fueled interest in both religion and religious liberty.

In the French and Indian War, British forces seized Canada from the French, but the francophone population remained politically isolated from the southern colonies. Excluding the Native Americans, who were being displaced, those thirteen colonies had a population of 2.6 million in 1770, about one-third that of Britain. Nearly one-fifth of those living in what would become the United States were black slaves.<sup class="reference" id="cite_ref-38">[38]

English expansion westward saw incorporation of disparate pre-established cultures it met. But it also found Amerindian resistance to that settlement. Their opposition took various forms across the continent, as allies with Europeans, multi-tribe nations, and alone -- by relocation and warring, by treaties and in court. On the other hand, English North American colonials were subject to British taxation, they had no representation in the Parliament of Great Britain.

Independence and expansion
The American Revolution was the first successful colonial war of independence against a European power. Americans strongly protested British efforts to impose taxes without the approval of colonial legislatures; the British insisted and tensions escalated to full-scale war in 1775, the American Revolutionary War.<sup class="reference" id="cite_ref-Humphrey2003_39-0">[39] On June 14, 1775, the Continental Congress, convening in Philadelphia, established a Continental Army under the command of George Washington.<sup class="reference" id="cite_ref-Brown2001_40-0">[40] Proclaiming that "all men are created equal" and endowed with "certain unalienable Rights", the Congress adopted the Declaration of Independence, drafted largely by Thomas Jefferson, on July 4, 1776. That date is now celebrated annually as America's Independence Day. In 1777, the Articles of Confederation established a weak government that operated until 1789.<sup class="reference" id="cite_ref-YoungNash2011_41-0">[41] After the British defeat at Yorktown by American forces assisted by the French, Great Britain recognized the independence of the United States and its sovereignty over most territory east of the Mississippi River.<sup class="reference" id="cite_ref-Banner2007mnb_42-0">[42] Nationalists calling for a strong federal government with powers of taxation led the constitutional convention in 1787.<sup class="reference" id="cite_ref-Morton2006wet_43-0">[43] The United States Constitution was ratified in 1788, and the new republic's first Senate, House of Representatives, and president—George Washington—took office in 1789.<sup class="reference" id="cite_ref-BoyerJr.2007_44-0">[44] The Bill of Rights, forbidding federal restriction of personal freedoms and guaranteeing a range of legal protections, was adopted in 1791.<sup class="reference" id="cite_ref-BoyerJr.2007_44-1">[44]

Attitudes toward slavery were shifting; most states outlawed the international slave trade, as did the federal government in 1808.<sup class="reference" id="cite_ref-Cogliano2008_45-0">[45] All the Northern states abolished slavery between 1780 and 1804, leaving the slave states of the South as defenders of the "peculiar institution". With cotton a highly profitable plantation crop after 1820, Southern whites increasingly decided slavery was a positive good for everyone, including the slaves.<sup class="reference" id="cite_ref-Hall200as2_46-0">[46] The Second Great Awakening, beginning about 1800, converted millions to evangelical Protestantism. In the North energized multiple social reform movements, including abolitionism.<sup class="reference" id="cite_ref-Clark2012iu_47-0">[47]

Americans' eagerness to expand westward prompted a long series of Indian Wars.<sup class="reference" id="cite_ref-BillingtonRidge2001j_48-0">[48] The Louisiana Purchase of French-claimed territory under President Thomas Jefferson in 1803 almost doubled the nation's size.<sup class="reference" id="cite_ref-49">[49] The War of 1812, declared against Britain over various grievances and fought to a draw, strengthened U.S. nationalism.<sup class="reference" id="cite_ref-Wait1999_50-0">[50]

A series of U.S. military incursions into Florida led Spain to cede it and other Gulf Coast territory in 1819.<sup class="reference" id="cite_ref-KloseJones1994_51-0">[51] The Trail of Tears in the 1830s exemplified the Indian removal policy that moved Indians to their own reservations with annual government subsidies. The United States annexed the Republic of Texas in 1845, amid a period when the concept of Manifest Destiny was becoming popular.<sup class="reference" id="cite_ref-Morrison1999_52-0">[52] The 1846 Oregon Treaty with Britain led to U.S. control of the present-day American Northwest.<sup class="reference" id="cite_ref-Kemp2010_53-0">[53] The U.S. victory in the Mexican-American War resulted in the 1848 cession of California and much of the present-day American Southwest.<sup class="reference" id="cite_ref-McIlwraithMuller2001_54-0">[54]

The California Gold Rush of 1848–49 further spurred western migration.<sup class="reference" id="cite_ref-Smith-Baranzini1999_55-0">[55] New railways made relocation easier for settlers and increased conflicts with Native Americans.<sup class="reference" id="cite_ref-Black2011kj_56-0">[56] Over a half-century, up to 40 million American bison, or buffalo, were slaughtered for skins and meat and to ease the railways' spread.<sup class="reference" id="cite_ref-Wishart2004_57-0">[57] The loss of the buffalo, a primary resource for the plains Indians, was an existential blow to many native cultures.<sup class="reference" id="cite_ref-Wishart2004_57-1">[57]

Slavery, civil war and industrialization
Tensions between slave and free states mounted with arguments about the relationship between the state and federal governments, as well as violent conflicts over the spread of slavery into new states.<sup class="reference" id="cite_ref-Murray2004kjh_58-0">[58] Abraham Lincoln, candidate of the largely antislavery Republican Party, was elected president in 1860.<sup class="reference" id="cite_ref-McIlwraithMuller2001mju_59-0">[59] Before he took office, seven slave states declared their secession—which the federal government maintained was illegal—and formed the Confederate States of America.<sup class="reference" id="cite_ref-O.27Brien2002qs_60-0">[60] With the Confederate attack upon Fort Sumter, the Civil War began and four more slave states joined the Confederacy.<sup class="reference" id="cite_ref-O.27Brien2002qs_60-1">[60] Lincoln's Emancipation Proclamation in 1863 declared slaves in the Confederacy to be free. Following the Union victory in 1865, three amendments to the U.S. Constitution ensured freedom for the nearly four million African Americans who had been slaves,<sup class="reference" id="cite_ref-61">[61] made them citizens, and gave them voting rights. The war and its resolution led to a substantial increase in federal power.<sup class="reference" id="cite_ref-62">[62] The war remains the deadliest conflict in American history, resulting in the deaths of 620,000 soldiers.<sup class="reference" id="cite_ref-63">[63]

After the war, the assassination of Abraham Lincoln radicalized Republican Reconstruction policies aimed at reintegrating and rebuilding the Southern states while ensuring the rights of the newly freed slaves.<sup class="reference" id="cite_ref-Tarr2009_64-0">[64] The resolution of the disputed 1876 presidential election by the Compromise of 1877 ended Reconstruction; Jim Crow laws soon disenfranchised many African Americans.<sup class="reference" id="cite_ref-Tarr2009_64-1">[64]

In the North, urbanization and an unprecedented influx of immigrants from Southern and Eastern Europe hastened the country's industrialization. The wave of immigration, lasting until 1924, provided labor and transformed American culture.<sup class="reference" id="cite_ref-Powell2009qwet_65-0">[65] National infrastructure development spurred economic growth.

The 1867 Alaska Purchase from Russia completed the country's mainland expansion. The Wounded Knee Massacre in 1890 was the last major armed conflict of the Indian Wars. In 1893, the indigenous monarchy of the Pacific Kingdom of Hawaii was overthrown in a coup led by American residents; the United States annexed the archipelago in 1898. Victory in the Spanish–American War the same year demonstrated that the United States was a world power and led to the annexation of Puerto Rico, Guam, and the Philippines.<sup class="reference" id="cite_ref-66">[66] The Philippines gained independence a half-century later; Puerto Rico and Guam remain U.S. territories.

World War I, Great Depression, and World War II
At the outbreak of World War I in 1914, the United States remained neutral. Most Americans sympathized with the British and French, although many opposed intervention.<sup class="reference" id="cite_ref-67">[67] In 1917, the United States joined the Allies, and the American Expeditionary Forces helped to turn the tide against the Central Powers. After the war, the Senate did not ratify the Treaty of Versailles, which established the League of Nations.<sup class="reference" id="cite_ref-autogenerated418_68-0">[68] The country pursued a policy of unilateralism, verging on isolationism.<sup class="reference" id="cite_ref-autogenerated418_68-1">[68] In 1920, the women's rights movement won passage of a constitutional amendment granting women's suffrage. The prosperity of the Roaring Twenties ended with the Wall Street Crash of 1929 that triggered the Great Depression. After his election as president in 1932, Franklin D. Roosevelt responded with the New Deal, a range of policies increasing government intervention in the economy, including the establishment of the Social Security system.<sup class="reference" id="cite_ref-69">[69] The Dust Bowl of the mid-1930s impoverished many farming communities and spurred a new wave of western migration.

The United States, effectively neutral during World War II's early stages after Nazi Germany's invasion of Poland in September 1939, began supplying materiel to the Allies in March 1941 through the Lend-Lease program. On December 7, 1941, the Empire of Japan launched a surprise attack on Pearl Harbor, prompting the United States to join the Allies against the Axis powers as well as the internment of Japanese Americans by the thousands.<sup class="reference" id="cite_ref-70">[70] Participation in the war spurred capital investment and industrial capacity. Among the major combatants, the United States was the only nation to become richer—indeed, far richer—instead of poorer because of the war.<sup class="reference" id="cite_ref-71">[71]

Allied conferences at Bretton Woods and Yalta outlined a new system of international organizations that placed the United States and Soviet Union at the center of world affairs. As victory was won in Europe, a 1945 international conference held in San Francisco produced the United Nations Charter, which became active after the war.<sup class="reference" id="cite_ref-72">[72] The United States, having developed the first nuclear weapons, used them on the Japanese cities of Hiroshima and Nagasaki in August. Japan surrendered on September 2, ending the war.<sup class="reference" id="cite_ref-73">[73]

Cold War and protest politics
[http://en.wikipedia.org/wiki/Martin_Luther_King,_Jr. Martin Luther King, Jr.] delivering his "I Have a Dream" speech, 1963.The United States and the Soviet Union jockeyed for power after World War II during the Cold War, dominating the military affairs of Europe through NATO and the Warsaw Pact, respectively. While they engaged in proxy wars and developed powerful nuclear arsenals, the two countries avoided direct military conflict. The U.S. often opposed Third World left-wing movements that it viewed as Soviet-sponsored. American troops fought Communist Chinese and North Korean forces in the Korean War of 1950–53. The House Un-American Activities Committee pursued a series of investigations into suspected leftist subversion, while Senator Joseph McCarthy became the figurehead of anticommunist sentiment.

The 1961 Soviet launch of the first manned spaceflight prompted President John F. Kennedy's call for the United States to be first to land "a man on the moon", achieved in 1969. Kennedy also faced a tense nuclear showdown with Soviet forces in Cuba. Meanwhile, the United States experienced sustained economic expansion. Amidst the presence of various white nationalist groups, particularly the Ku Klux Klan, a growing civil rights movement used nonviolence to confront segregation and discrimination. This was symbolized and led by black Americans such as Rosa Parks and [http://en.wikipedia.org/wiki/Martin_Luther_King,_Jr. Martin Luther King, Jr.]. On the other hand, some black nationalist groups such as the Black Panther Party had a more militant scope.

Following Kennedy's assassination in 1963, the Civil Rights Act of 1964 and Voting Rights Act of 1965 were passed under President Lyndon B. Johnson.<sup class="reference" id="cite_ref-74">[74] <sup class="reference" id="cite_ref-75">[75] He also signed into law the Medicare and Medicaid programs.<sup class="reference" id="cite_ref-76">[76] Johnson and his successor, Richard Nixon, expanded a proxy war in Southeast Asia into the unsuccessful Vietnam War. A widespread countercultural movement grew, fueled by opposition to the war, black nationalism, and the sexual revolution. Betty Friedan, Gloria Steinem, and others led a new wave of feminism that sought political, social, and economic equality for women.

As a result of the Watergate scandal, in 1974 Nixon became the first U.S. president to resign, to avoid being impeached on charges including obstruction of justice and abuse of power. The Jimmy Carter administration of the late 1970s was marked by stagflation and the Iran hostage crisis. The election of Ronald Reagan as president in 1980 heralded a rightward shift in American politics, reflected in major changes in taxation and spending priorities. His second term in office brought both the Iran-Contra scandal and significant diplomatic progress with the Soviet Union. The subsequent Soviet collapse ended the Cold War.

Contemporary era
September 11 attacks on World Trade CenterUnder President George H. W. Bush, the United States took a lead role in the UN–sanctioned Gulf War. The longest economic expansion in modern U.S. history—from March 1991 to March 2001—encompassed the Bill Clinton administration and the dot-com bubble.<sup class="reference" id="cite_ref-77">[77] A civil lawsuit and sex scandal led to Clinton's impeachment in 1998, but he remained in office. The 2000 presidential election, one of the closest in American history, was resolved by a U.S. Supreme Court decision—George W. Bush, son of George H. W. Bush, became president.

On September 11, 2001, al-Qaeda terrorists struck the World Trade Center in New York City and The Pentagon near Washington, D.C., killing nearly three thousand people. In response, the Bush administration launched the global War on Terror, invading Afghanistan and removing the Taliban government and al-Qaeda training camps. Taliban insurgents continue to fight a guerrilla war. In 2002, the Bush administration began to press for regime change in Iraq on controversial grounds.<sup class="reference" id="cite_ref-78">[78]

Forces led by the U.S. invaded Iraq in 2003, ousting Saddam Hussein. In 2005, Hurricane Katrina caused severe destruction along much of the Gulf Coast, devastating New Orleans. In 2008, amid a global economic recession, the first African American president, Barack Obama, was elected. Major health care and financial system reforms were enacted two years later. In 2011, a raid by Navy SEALs in Pakistan killed al-Qaeda leader Osama bin Laden. The Iraq War officially ended with the pullout of the remaining U.S. troops from the country in December 2011.

Government and politics
Main articles: Federal government of the United States, state governments of the United States, and elections in the United StatesThe United States is the world's oldest surviving federation. It is a constitutional republic and representative democracy, "in which majority rule is tempered by minority rights protected by law".<sup class="reference" id="cite_ref-79">[79] The government is regulated by a system of checks and balances defined by the U.S. Constitution, which serves as the country's supreme legal document.<sup class="reference" id="cite_ref-80">[80]

In the American federalist system, citizens are usually subject to three levels of government, federal, state, and local; the local government's duties are commonly split between county and municipal governments. In almost all cases, executive and legislative officials are elected by a plurality vote of citizens by district. There is no proportional representation at the federal level, and it is very rare at lower levels. The federal government is composed of three branches: The House of Representatives has 435 voting members, each representing a congressional district for a two-year term. House seats are apportioned among the states by population every tenth year. As of the 2000 census, seven states have the minimum of one representative, while California, the most populous state, has fifty-three.<sup class="reference" id="cite_ref-84">[84]
 * Legislative: The bicameral Congress, made up of the Senate and the House of Representatives, makes federal law, declares war, approves treaties, has the power of the purse,<sup class="reference" id="cite_ref-81">[81] and has the power of impeachment, by which it can remove sitting members of the government.<sup class="reference" id="cite_ref-82">[82]
 * Executive: The president is the commander-in-chief of the military, can veto legislative bills before they become law (subject to Congressional override), and appoints the members of the Cabinet (subject to Senate approval) and other officers, who administer and enforce federal laws and policies.<sup class="reference" id="cite_ref-83">[83]
 * Judicial: The Supreme Court and lower federal courts, whose judges are appointed by the president with Senate approval, interpret laws and overturn those they find unconstitutional.

The Senate has 100 members with each state having two senators, elected at-large to six-year terms; one third of Senate seats are up for election every other year. The president serves a four-year term and may be elected to the office no more than twice. The president is not elected by direct vote, but by an indirect electoral college system in which the determining votes are apportioned to the states and the District of Columbia.<sup class="reference" id="cite_ref-85">[85] The Supreme Court, led by the Chief Justice of the United States, has nine members, who serve for life.<sup class="reference" id="cite_ref-86">[86]

The state governments are structured in roughly similar fashion; Nebraska uniquely has a unicameral legislature.<sup class="reference" id="cite_ref-87">[87] The governor (chief executive) of each state is directly elected. Some state judges and cabinet officers are appointed by the governors of the respective states, while others are elected by popular vote.

The original text of the Constitution establishes the structure and responsibilities of the federal government and its relationship with the individual states. Article One protects the right to the "great writ" of habeas corpus, and Article Three guarantees the right to a jury trial in all criminal cases. Amendments to the Constitution require the approval of three-fourths of the states. The Constitution has been amended twenty-seven times;<sup class="reference" id="cite_ref-88">[88] the first ten amendments, which make up the Bill of Rights, and the Fourteenth Amendment form the central basis of Americans' individual rights. All laws and governmental procedures are subject to judicial review and any law ruled in violation of the Constitution is voided. The principle of judicial review, not explicitly mentioned in the Constitution, was declared by the Supreme Court in Marbury v. Madison (1803).<sup class="reference" id="cite_ref-89">[89]

Parties and ideology
Main articles: Politics of the United States and Political ideologies in the United StatesCurrent president Barack Obama taking the presidential oath from Chief Justice John Roberts, January 20, 2009The United States has operated under a two-party system for most of its history.<sup class="reference" id="cite_ref-twsNovGe_90-0">[90] For elective offices at most levels, state-administered primary elections choose the major party nominees for subsequent general elections. Since the general election of 1856, the major parties have been the Democratic Party, founded in 1824, and the Republican Party, founded in 1854. Since the Civil War, only one third-party presidential candidate—former president Theodore Roosevelt, running as a Progressive in 1912—has won as much as 20% of the popular vote. The third-largest political party is the Libertarian Party.

Within American political culture, the Republican Party is considered center-right or conservative and the Democratic Party is considered center-left or liberal.<sup class="reference" id="cite_ref-91">[91] The states of the Northeast and West Coast and some of the Great Lakes states, known as "blue states", are relatively liberal. The "red states" of the South and parts of the Great Plains and Rocky Mountains are relatively conservative.

The winner of the 2008 presidential election, Democrat Barack Obama, is the 44th U.S. president; although, he is the 43rd person sworn into office, as Grover Cleveland served two non-consecutive terms and is counted chronologically as both the 22nd and 24th president.

The 2010 midterm elections saw the Republican Party take control of the House and make gains in the Senate, where the Democrats retain the majority. In the 112th United States Congress, the Senate consists of 51 Democrats, two independents who caucus with the Democrats, and 47 Republicans; the House consists of 242 Republicans and 192 Democrats—one seat is vacant. There are 29 Republican and 20 Democratic state governors, as well as one independent.<sup class="reference" id="cite_ref-92">[92]

Since the founding of the United States until 2000s, the country's governance has been primarily dominated by White Anglo-Saxon Protestants (WASPs). However, the situation has changed recently and of the top 17 positions (four national candidates of the two major party in the 2012 U.S. presidential election, four leaders in 112th United States Congress, and nine Supreme Court Justices) there is only one WASP.<sup class="reference" id="cite_ref-93">[93] <sup class="reference" id="cite_ref-94">[94] <sup class="reference" id="cite_ref-95">[95]

Foreign relations and military
Main articles: Foreign relations of the United States, Foreign policy of the United States, and United States Armed ForcesBritish Foreign Secretary William Hague and U.S. Secretary of State Hillary Clinton, May 2010The United States exercises global economic, political, and military influence. It is a permanent member of the United Nations Security Council and New York City hosts the United Nations Headquarters. It is a member of the G8,<sup class="reference" id="cite_ref-96">[96] G20, and Organisation for Economic Co-operation and Development. Almost all countries have embassies in Washington, D.C., and many have consulates around the country. Likewise, nearly all nations host American diplomatic missions. However, Cuba, Iran, North Korea, Bhutan, and the Republic of China (Taiwan) do not have formal diplomatic relations with the United States (although the US still supplies Taiwan with military equipment).

The United States has a "special relationship" with the United Kingdom<sup class="reference" id="cite_ref-97">[97] and strong ties with Canada,<sup class="reference" id="cite_ref-98">[98] Australia,<sup class="reference" id="cite_ref-99">[99] New Zealand,<sup class="reference" id="cite_ref-100">[100] the Philippines,<sup class="reference" id="cite_ref-101">[101] Japan,<sup class="reference" id="cite_ref-102">[102] South Korea,<sup class="reference" id="cite_ref-103">[103] and Israel<sup class="reference" id="cite_ref-104">[104] and several European countries such as France and Germany. It works closely with fellow NATO members on military and security issues and with its neighbors through the Organization of American States and free trade agreements such as the trilateral North American Free Trade Agreement with Canada and Mexico. In 2008, the United States spent a net $25.4 billion on official development assistance, the most in the world. As a share of America's large gross national income (GNI), however, the U.S. contribution of 0.18% ranked last among twenty-two donor states. By contrast, private overseas giving by Americans is relatively generous.<sup class="reference" id="cite_ref-105">[105] The USS Abraham Lincoln aircraft carrier.The president holds the title of commander-in-chief of the nation's armed forces and appoints its leaders, the secretary of defense and the Joint Chiefs of Staff. The United States Department of Defense administers the armed forces, including the Army, Navy, Marine Corps, and Air Force. The Coast Guard is run by the Department of Homeland Security in peacetime and the Department of the Navy in time of war. In 2008, the armed forces had 1.4 million personnel on active duty. The Reserves and National Guard brought the total number of troops to 2.3 million. The Department of Defense also employed about 700,000 civilians, not including contractors.<sup class="reference" id="cite_ref-106">[106]

Military service is voluntary, though conscription may occur in wartime through the Selective Service System.<sup class="reference" id="cite_ref-107">[107] American forces can be rapidly deployed by the Air Force's large fleet of transport aircraft, the Navy's eleven active aircraft carriers, and Marine Expeditionary Units at sea with the Navy's Atlantic and Pacific fleets. The military operates 865 bases and facilities abroad,<sup class="reference" id="cite_ref-108">[108] and maintains deployments greater than 100 active duty personnel in 25 foreign countries.<sup class="reference" id="cite_ref-109">[109] The extent of this global military presence has prompted some scholars to describe the United States as maintaining an "empire of bases".<sup class="reference" id="cite_ref-110">[110]

Total U.S. military spending in 2010, almost $700 billion, was 43% of global military spending and greater than the next fourteen largest national military expenditures combined. At 4.8% of GDP, the rate was the second-highest among the top fifteen military spenders, after Saudi Arabia.<sup class="reference" id="cite_ref-111">[111] US defense spending as a percentage of GDP ranks 24th globally as of 2010 according to the CIA.<sup class="reference" id="cite_ref-112">[112] Defense's share of US spending has generally declined in recent decades, from Cold War peaks of 14.2% of GDP in 1953 and 69.5% of federal outlays in 1954 to 4.7% of GDP and 18.8% of federal outlays in 2011.<sup class="reference" id="cite_ref-113">[113] The proposed base Department of Defense budget for 2012, $553 billion, is a 4.2% increase over 2011; an additional $118 billion is proposed for the military campaigns in Iraq and Afghanistan.<sup class="reference" id="cite_ref-114">[114] The last American troops serving in Iraq departed in December 2011;<sup class="reference" id="cite_ref-115">[115] 4,484 servicemen were killed during the Iraq War.<sup class="reference" id="cite_ref-116">[116] Approximately 90,000 U.S. troops were serving in Afghanistan as of April 2012;<sup class="reference" id="cite_ref-Frontline_Turning_Point_117-0">[117] as of April 4, 1,924 had been killed during the War in Afghanistan.<sup class="reference" id="cite_ref-118">[118]

Economy
Main article: Economy of the United States The United States has a capitalist mixed economy, which is fueled by abundant natural resources, a well-developed infrastructure, and high productivity.<sup class="reference" id="cite_ref-126">[126] According to the International Monetary Fund, the U.S. GDP of $15.1 trillion constitutes 22% of the gross world product at market exchange rates and over 19% of the gross world product at purchasing power parity (PPP).<sup class="reference" id="cite_ref-IMF_GDP_3-6">[3] Though larger than any other nation's, its national GDP was about 5% smaller at PPP in 2011 than the European Union's, whose population is around 62% higher.<sup class="reference" id="cite_ref-127">[127] The country ranks ninth in the world in nominal GDP per capita and sixth in GDP per capita at PPP.<sup class="reference" id="cite_ref-IMF_GDP_3-7">[3] The U.S. dollar is the world's primary reserve currency.<sup class="reference" id="cite_ref-128">[128]

The United States is the largest importer of goods and second largest exporter, though exports per capita are relatively low. In 2010, the total U.S. trade deficit was $635 billion.<sup class="reference" id="cite_ref-Trade_129-0">[129] Canada, China, Mexico, Japan, and Germany are its top trading partners.<sup class="reference" id="cite_ref-130">[130] In 2010, oil was the largest import commodity, while transportation equipment was the country's largest export.<sup class="reference" id="cite_ref-Trade_129-1">[129] China is the largest foreign holder of U.S. public debt.<sup class="reference" id="cite_ref-131">[131] New York Stock Exchange on Wall Street, world's largest stock exchange per total market capitalization of its listed companies.<sup class="reference" id="cite_ref-132">[132] In 2009, the private sector was estimated to constitute 86.4% of the economy, with federal government activity accounting for 4.3% and state and local government activity (including federal transfers) the remaining 9.3%.<sup class="reference" id="cite_ref-133">[133] While its economy has reached a postindustrial level of development and its service sector constitutes 67.8% of GDP, the United States remains an industrial power.<sup class="reference" id="cite_ref-Econ_134-0">[134] The leading business field by gross business receipts is wholesale and retail trade; by net income it is manufacturing.<sup class="reference" id="cite_ref-135">[135]

Chemical products are the leading manufacturing field.<sup class="reference" id="cite_ref-136">[136] The United States is the third largest producer of oil in the world, as well as its largest importer.<sup class="reference" id="cite_ref-137">[137] It is the world's number one producer of electrical and nuclear energy, as well as liquid natural gas, sulfur, phosphates, and salt. While agriculture accounts for just under 1% of GDP,<sup class="reference" id="cite_ref-Econ_134-1">[134] the United States is the world's top producer of corn<sup class="reference" id="cite_ref-138">[138] and soybeans.<sup class="reference" id="cite_ref-139">[139] Coca-Cola and McDonald's are the two most recognized brands in the world.<sup class="reference" id="cite_ref-140">[140]

In August 2010, the American labor force consisted of 154.1 million people. With 21.2 million people, government is the leading field of employment. The largest private employment sector is health care and social assistance, with 16.4 million people. About 12% of workers are unionized, compared to 30% in Western Europe.<sup class="reference" id="cite_ref-141">[141] The World Bank ranks the United States first in the ease of hiring and firing workers.<sup class="reference" id="cite_ref-EDBI_142-0">[142]

The 2008-2012 global recession affected the United States quite badly. For example, persistent high unemployment remains, along with low consumer confidence, the continuing decline in home values and increase in foreclosures and personal bankruptcies, an escalating federal debt crisis, inflation, and rising petroleum and food prices. In fact, a 2011 poll found that more than half of all Americans think the U.S. is still in recession or even depression, despite official data that shows a historically modest recovery.<sup class="reference" id="cite_ref-143">[143] In 2009, the United States had the third highest labor productivity per person in the world, behind Luxembourg and Norway. It was fourth in productivity per hour, behind those two countries and the Netherlands.<sup class="reference" id="cite_ref-144">[144] Compared to Europe, U.S. property and corporate income tax rates are generally higher, while labor and, particularly, consumption tax rates are lower.<sup class="reference" id="cite_ref-145">[145]

Geography and environment
Main articles: Geography of the United States, Climate of the United States, and Environment of the United StatesThe land area of the contiguous United States is 2,959,064 square miles (7,663,941 km2). Alaska, separated from the contiguous United States by Canada, is the largest state at 663,268 square miles (1,717,856 km2). Hawaii, occupying an archipelago in the central Pacific, southwest of North America, is 10,931 square miles (28,311 km2) in area.<sup class="reference" id="cite_ref-146">[146]

The United States is the world's third or fourth largest nation by total area (land and water), ranking behind Russia and Canada and just above or below China. The ranking varies depending on how two territories disputed by China and India are counted and how the total size of the United States is measured: calculations range from 3,676,486 square miles (9,522,055 km2)<sup class="reference" id="cite_ref-147">[147] to 3,717,813 square miles (9,629,091 km2)<sup class="reference" id="cite_ref-148">[148] to 3,794,101 square miles (9,826,676 km2).<sup class="reference" id="cite_ref-WF_1-2">[1] Measured by only land area, the United States is third in size behind Russia and China, just ahead of Canada.<sup class="reference" id="cite_ref-149">[149] The Bald Eagle, the national bird of the United States since 1782.The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont. The Appalachian Mountains divide the eastern seaboard from the Great Lakes and the grasslands of the Midwest. The Mississippi–Missouri River, the world's fourth longest river system, runs mainly north–south through the heart of the country. The flat, fertile prairie of the Great Plains stretches to the west, interrupted by a highland region in the southeast.

The Rocky Mountains, at the western edge of the Great Plains, extend north to south across the country, reaching altitudes higher than 14,000 feet (4,300 m) in Colorado. Farther west are the rocky Great Basin and deserts such as the Chihuahua and Mojave. The Sierra Nevada and Cascade mountain ranges run close to the Pacific coast, both ranges reaching altitudes higher than 14,000 feet.

The lowest and highest points in the continental United States are in the state of California, and only about 80 miles apart. At 20,320 feet (6,194 m), Alaska's Mount McKinley is the tallest peak in the country and in North America. Active volcanoes are common throughout Alaska's Alexander and Aleutian Islands, and Hawaii consists of volcanic islands. The supervolcano underlying Yellowstone National Park in the Rockies is the continent's largest volcanic feature.<sup class="reference" id="cite_ref-150">[150]

The United States, with its large size and geographic variety, includes most climate types. To the east of the 100th meridian, the climate ranges from humid continental in the north to humid subtropical in the south. The southern tip of Florida is tropical, as is Hawaii. The Great Plains west of the 100th meridian are semi-arid. Much of the Western mountains are alpine. The climate is arid in the Great Basin, desert in the Southwest, Mediterranean in coastal California, and oceanic in coastal Oregon and Washington and southern Alaska. Most of Alaska is subarctic or polar. Extreme weather is not uncommon—the states bordering the Gulf of Mexico are prone to hurricanes, and most of the world's tornadoes occur within the country, mainly in the Midwest's Tornado Alley.<sup class="reference" id="cite_ref-151">[151]

The U.S. ecology is considered "megadiverse": about 17,000 species of vascular plants occur in the contiguous United States and Alaska, and over 1,800 species of flowering plants are found in Hawaii, few of which occur on the mainland.<sup class="reference" id="cite_ref-152">[152] The United States is home to more than 400 mammal, 750 bird, and 500 reptile and amphibian species.<sup class="reference" id="cite_ref-153">[153] About 91,000 insect species have been described.<sup class="reference" id="cite_ref-154">[154]

The Endangered Species Act of 1973 protects threatened and endangered species and their habitats, which are monitored by the United States Fish and Wildlife Service. There are fifty-eight national parks and hundreds of other federally managed parks, forests, and wilderness areas.<sup class="reference" id="cite_ref-155">[155] Altogether, the government owns 28.8% of the country's land area.<sup class="reference" id="cite_ref-FL_156-0">[156] Most of this is protected, though some is leased for oil and gas drilling, mining, logging, or cattle ranching; 2.4% is used for military purposes.<sup class="reference" id="cite_ref-FL_156-1">[156]

Political divisions
Main articles: Political divisions of the United States, U.S. state, and Territories of the United StatesFurther information: Territorial evolution of the United States and United States territorial acquisitionsThe United States is a federal union of fifty states. The original thirteen states were the successors of the thirteen colonies that rebelled against British rule. Early in the country's history, three new states were organized on territory separated from the claims of the existing states: Kentucky from Virginia; Tennessee from North Carolina; and Maine from Massachusetts. Most of the other states have been carved from territories obtained through war or purchase by the U.S. government. One set of exceptions includes Vermont, Texas, and Hawaii: each was an independent republic before joining the union. During the American Civil War, West Virginia broke away from Virginia. The most recent state—Hawaii—achieved statehood on August 21, 1959.<sup class="reference" id="cite_ref-157">[157] The states do not have the right to unilaterally secede from the union.

The states compose the vast bulk of the U.S. land mass; the two other areas considered integral parts of the country are the District of Columbia, the federal district where the capital, Washington, is located; and Palmyra Atoll, an uninhabited but incorporated territory in the Pacific Ocean. The United States also possesses five major overseas territories: Puerto Rico and the United States Virgin Islands in the Caribbean; and American Samoa, Guam, and the Northern Mariana Islands in the Pacific.<sup class="reference" id="cite_ref-158">[158] Those born in the major territories (except for American Samoa) possess U.S. citizenship.<sup class="reference" id="cite_ref-159">[159] American citizens residing in the territories have many of the same rights and responsibilities as citizens residing in the states; however, they are generally exempt from federal income tax, may not vote for president, and have only nonvoting representation in the U.S. Congress.<sup class="reference" id="cite_ref-160">[160]

The United States also observes tribal sovereignty of the Native Nations. Though reservations are within state borders, the reservation is a sovereign. While the United States recognizes this sovereignty, other countries may not.<sup class="reference" id="cite_ref-161">[161] ===Income and human development=== Main article: Income in the United StatesSee also: Income inequality in the United States, Poverty in the United States, and Affluence in the United StatesAccording to the United States Census Bureau, the pretax median household income in 2010 was $49,445. The median ranged from $64,308 among Asian American households to $32,068 among African American households.<sup class="reference" id="cite_ref-CBPR10_122-1">[122] Using purchasing power parity exchange rates, the overall median is similar to the most affluent cluster of developed nations. As of 2007, Americans had the second highest median equivalised disposable household income among OECD nations, behind only Luxembourg, and the highest average disposable income and employee earnings.<sup class="reference" id="cite_ref-162">[162] <sup class="reference" id="cite_ref-163">[163] After declining sharply during the middle of the 20th century, poverty rates have plateaued since the early 1970s, with 11–15% of Americans below the poverty line every year, and 58.5% spending at least one year in poverty between the ages of 25 and 75.<sup class="reference" id="cite_ref-USCB_IP.26HIC_2007_164-0">[164] <sup class="reference" id="cite_ref-165">[165] In 2010, 46.2 million Americans lived in poverty, a figure that rose for the fourth year in a row.<sup class="reference" id="cite_ref-CBPR10_122-2">[122] A middle-class suburban housing development in San Jose, California.The U.S. welfare state is one of the least extensive in the developed world, reducing both relative poverty and absolute poverty by considerably less than the mean for rich nations,<sup class="reference" id="cite_ref-Sme_166-0">[166] <sup class="reference" id="cite_ref-167">[167] though combined private and public social expenditures per capita are relatively high.<sup class="reference" id="cite_ref-168">[168] While the American welfare state effectively reduces poverty among the elderly,<sup class="reference" id="cite_ref-169">[169] it provides relatively little assistance to the young.<sup class="reference" id="cite_ref-170">[170] A 2007 UNICEF study of children's well-being in twenty-one industrialized nations ranked the United States next to last.<sup class="reference" id="cite_ref-171">[171]

Between 1947 and 1979, real median income rose by over 80% for all classes, with the incomes of poor Americans rising faster than those of the rich.<sup class="reference" id="cite_ref-Hartman_172-0">[172] However, income gains since then have been slower, less widely shared, and accompanied by increased economic insecurity.<sup class="reference" id="cite_ref-Hartman_172-1">[172] <sup class="reference" id="cite_ref-173">[173] Median household income has increased for all classes since 1980,<sup class="reference" id="cite_ref-174">[174] largely owing to more dual-earner households, the closing of the gender pay gap, and longer work hours, but the growth has been strongly tilted toward the very top.<sup class="reference" id="cite_ref-Sme_166-1">[166] <sup class="reference" id="cite_ref-Hartman_172-2">[172] <sup class="reference" id="cite_ref-175">[175]

Consequently, the share of income of the top 1%—21.8% of total reported income in 2005—has more than doubled since 1980,<sup class="reference" id="cite_ref-176">[176] leaving the United States with the greatest income inequality among developed nations.<sup class="reference" id="cite_ref-Sme_166-2">[166] <sup class="reference" id="cite_ref-177">[177] The United States has a progressive tax system which equates to higher income earners paying a larger percentage of their income in taxes.<sup class="reference" id="cite_ref-178">[178] The top 1% pays 27.6% of all federal taxes, while the top 10% pays 54.7%.<sup class="reference" id="cite_ref-179">[179]

Wealth, like income and taxes, is highly concentrated: The richest 10% of the adult population possesses 69.8% of the country's household wealth, the second-highest share among developed nations.<sup class="reference" id="cite_ref-180">[180] The top 1% possesses 33.4% of net wealth.<sup class="reference" id="cite_ref-181">[181] In 2011 the United Nations Development Programme ranked the United States 23rd among 139 countries on its inequality-adjusted human development index (IHDI), nineteen places lower than in the standard HDI.<sup class="reference" id="cite_ref-182">[182]

Science and technology
Main article: Science and technology in the United StatesSee also: Technological and industrial history of the United StatesNeil Armstrong was the first person to walk on the Moon.The United States has been a leader in scientific research and technological innovation since the late 19th century. In 1876, Alexander Graham Bell was awarded the first U.S. patent for the telephone. Thomas Edison's laboratory developed the phonograph, the first long-lasting light bulb, and the first viable movie camera.<sup class="reference" id="cite_ref-183">[183] Nikola Tesla pioneered alternating current, the AC motor, and radio. In the early 20th century, the automobile companies of Ransom E. Olds and Henry Ford popularized the assembly line. The Wright brothers, in 1903, made the first sustained and controlled heavier-than-air powered flight.<sup class="reference" id="cite_ref-184">[184]

The rise of Nazism in the 1930s led many European scientists, including Albert Einstein, Enrico Fermi, and John von Neumann, to immigrate to the United States. During World War II, the Manhattan Project developed nuclear weapons, ushering in the Atomic Age. The Space Race produced rapid advances in rocketry, materials science, and computers. IBM, [http://en.wikipedia.org/wiki/Apple_Inc. Apple Computer], and Microsoft refined and popularized the personal computer.

The United States largely developed the ARPANET and its successor, the Internet. Today, 64% of research and development funding comes from the private sector.<sup class="reference" id="cite_ref-185">[185] The United States leads the world in scientific research papers and impact factor.<sup class="reference" id="cite_ref-186">[186] As of April 2010, 68% of American households had broadband Internet service.<sup class="reference" id="cite_ref-187">[187] The country is the primary developer and grower of genetically modified food, representing half of the world's biotech crops.<sup class="reference" id="cite_ref-188">[188]

Transportation
The Interstate Highway System, which extends 46,876 miles (75,440 km)<sup class="reference" id="cite_ref-189">[189] Main article: Transportation in the United StatesPersonal transportation is dominated by automobiles, which operate on a network of 13 million roads,<sup class="reference" id="cite_ref-190">[190] including one of the world's longest highway systems.<sup class="reference" id="cite_ref-191">[191] The world's second largest automobile market,<sup class="reference" id="cite_ref-192">[192] the United States has the highest rate of per-capita vehicle ownership in the world, with 765 vehicles per 1,000 Americans.<sup class="reference" id="cite_ref-193">[193] About 40% of personal vehicles are vans, SUVs, or light trucks.<sup class="reference" id="cite_ref-194">[194] The average American adult (accounting for all drivers and nondrivers) spends 55 minutes driving every day, traveling 29 miles (47 km).<sup class="reference" id="cite_ref-195">[195]

Mass transit accounts for 9% of total U.S. work trips.<sup class="reference" id="cite_ref-196">[196] <sup class="reference" id="cite_ref-197">[197] While transport of goods by rail is extensive, relatively few people use rail to travel,<sup class="reference" id="cite_ref-198">[198] though ridership on Amtrak, the national intercity passenger rail system, grew by almost 37% between 2000 and 2010.<sup class="reference" id="cite_ref-199">[199] Also, Light rail development has increased in recent years.<sup class="reference" id="cite_ref-200">[200] Bicycle usage for work commutes is minimal.<sup class="reference" id="cite_ref-201">[201]

The civil airline industry is entirely privately owned and has been largely deregulated since 1978, while most major airports are publicly owned. The three largest airlines in the world by passengers carried are U.S.-based; Delta Air Lines is number one.<sup class="reference" id="cite_ref-202">[202] Of the world's thirty busiest passenger airports, sixteen are in the United States, including the busiest, Hartsfield-Jackson Atlanta International Airport.<sup class="reference" id="cite_ref-203">[203]

Energy
See also: Energy policy of the United StatesThe United States energy market is 29,000 terawatt hours per year. Energy consumption per capita is 7.8 tons of oil equivalent per year, the 10th highest rate in the world. In 2005, 40% of this energy came from petroleum, 23% from coal, and 22% from natural gas. The remainder was supplied by nuclear power and renewable energy sources.<sup class="reference" id="cite_ref-204">[204] The United States is the world's largest consumer of petroleum.<sup class="reference" id="cite_ref-205">[205] For decades, nuclear power has played a limited role relative to many other developed countries, in part due to public perception in the wake of a 1979 accident. In 2007, several applications for new nuclear plants were filed.<sup class="reference" id="cite_ref-206">[206] The United States has 27% of global coal reserves.<sup class="reference" id="cite_ref-BPReview_207-0">[207]

Education
Some 80% of U.S. college students attend public universities such as the University of Virginia, founded by Thomas Jefferson.<sup class="reference" id="cite_ref-208">[208] Main article: Education in the United StatesSee also: Educational attainment in the United States and Higher education in the United StatesAmerican public education is operated by state and local governments, regulated by the United States Department of Education through restrictions on federal grants. Children are required in most states to attend school from the age of six or seven (generally, kindergarten or first grade) until they turn eighteen (generally bringing them through twelfth grade, the end of high school); some states allow students to leave school at sixteen or seventeen.<sup class="reference" id="cite_ref-209">[209] About 12% of children are enrolled in parochial or nonsectarian private schools. Just over 2% of children are homeschooled.<sup class="reference" id="cite_ref-210">[210]

The United States has many competitive private and public institutions of higher education. According to prominent international rankings, 13 or 15 American colleges and universities are ranked among the top 20 in the world.<sup class="reference" id="cite_ref-211">[211] <sup class="reference" id="cite_ref-212">[212] There are also local community colleges with generally more open admission policies, shorter academic programs, and lower tuition. Of Americans twenty-five and older, 84.6% graduated from high school, 52.6% attended some college, 27.2% earned a bachelor's degree, and 9.6% earned graduate degrees.<sup class="reference" id="cite_ref-213">[213] The basic literacy rate is approximately 99%.<sup class="reference" id="cite_ref-WF_1-3">[1] <sup class="reference" id="cite_ref-214">[214] The United Nations assigns the United States an Education Index of 0.97, tying it for 12th in the world.<sup class="reference" id="cite_ref-215">[215]

Health
See also: Health care in the United States, Health care reform in the United States, and Health insurance in the United StatesThe Texas Medical Center in Houston, the world's largest medical center<sup class="reference" id="cite_ref-216">[216] The United States life expectancy of 78.4 years at birth ranks it 50th among 221 nations.<sup class="reference" id="cite_ref-217">[217] Increasing obesity in the United States and health improvements elsewhere have contributed to lowering the country's rank in life expectancy from 1987, when it was 11th in the world.<sup class="reference" id="cite_ref-218">[218] Obesity rates in the United States are among the highest in the world.<sup class="reference" id="cite_ref-219">[219] Approximately one-third of the adult population is obese and an additional third is overweight;<sup class="reference" id="cite_ref-220">[220] the obesity rate, the highest in the industrialized world, has more than doubled in the last quarter-century.<sup class="reference" id="cite_ref-221">[221] Obesity-related type 2 diabetes is considered epidemic by health care professionals.<sup class="reference" id="cite_ref-222">[222] The infant mortality rate of 6.06 per thousand places the United States 176th out of 222 countries.<sup class="reference" id="cite_ref-223">[223]

The US is a global leader in medical innovation. America solely developed or contributed significantly to 9 of the top 10 most important medical innovations since 1975 as ranked by a 2001 poll of physicians, while the EU and Switzerland together contributed to five. Since 1966 Americans have received more Nobel Prizes in Medicine than the rest of the world combined. From 1989 to 2002 four times more money was invested in private biotechnology companies in America than in Europe. <sup class="reference" id="cite_ref-224">[224] <sup class="reference" id="cite_ref-225">[225]

The U.S. health care system far outspends any other nation's, measured in both per capita spending and percentage of GDP.<sup class="reference" id="cite_ref-226">[226] Health care coverage in the United States is a combination of public and private efforts, and is not universal as in all other developed countries. In 2004, private insurance paid for 36% of personal health expenditures, private out-of-pocket payments covered 15%, and federal, state, and local governments paid for 44%.<sup class="reference" id="cite_ref-CDC_H_227-0">[227]

In 2005, 46.6 million Americans, 15.9% of the population, were uninsured, 5.4 million more than in 2001. The main cause of this rise is the drop in the number of Americans with employer-sponsored health insurance.<sup class="reference" id="cite_ref-CBPP_228-0">[228] The subject of uninsured and underinsured Americans is a major political issue.<sup class="reference" id="cite_ref-229">[229] <sup class="reference" id="cite_ref-230">[230] In 2006, Massachusetts became the first state to mandate universal health insurance.<sup class="reference" id="cite_ref-231">[231] Federal legislation passed in early 2010 would ostensibly create a near-universal health insurance system around the country by 2014, though the bill and its ultimate impact are issues of controversy. <sup class="reference" id="cite_ref-232">[232] <sup class="reference" id="cite_ref-233">[233]

Crime and law enforcement
Main articles: Law enforcement in the United States and Crime in the United StatesSee also: Law of the United States, Incarceration in the United States, Capital punishment in the United States, and Second Amendment to the United States ConstitutionLaw enforcement in the U.S. is maintained primarily by local police departments. The New York City Police Department (NYPD) is the largest in the country.<sup class="reference" id="cite_ref-234">[234] Law enforcement in the United States is primarily the responsibility of local police and sheriff's departments, with state police providing broader services. Federal agencies such as the Federal Bureau of Investigation (FBI) and the U.S. Marshals Service have specialized duties.<sup class="reference" id="cite_ref-235">[235] At the federal level and in almost every state, jurisprudence operates on a common law system.

State courts conduct most criminal trials; federal courts handle certain designated crimes as well as certain appeals from the state systems. Federal law prohibits a variety of drugs, although states sometimes pass laws in conflict with federal regulations. The smoking age is generally 18, and the drinking age is generally 21.

Among developed nations, the United States has above-average levels of violent crime and particularly high levels of gun violence and homicide.<sup class="reference" id="cite_ref-236">[236] There were 5.0 murders per 100,000 persons in 2009, 10.4% fewer than in 2000.<sup class="reference" id="cite_ref-Crime_US_Murder_2010-09_237-0">[237] Gun ownership rights are the subject of contentious political debate.

The United States has the highest documented incarceration rate<sup class="reference" id="cite_ref-SP_238-0">[238] and total prison population<sup class="reference" id="cite_ref-239">[239] in the world. At the start of 2008, more than 2.3 million people were incarcerated, more than one in every 100 adults.<sup class="reference" id="cite_ref-240">[240] The current rate is about seven times the 1980 figure,<sup class="reference" id="cite_ref-241">[241] and over three times the figure in Poland, the Organisation for Economic Co-operation and Development (OECD) country with the next highest rate.<sup class="reference" id="cite_ref-242">[242] African American males are jailed at about six times the rate of white males and three times the rate of Hispanic males.<sup class="reference" id="cite_ref-SP_238-1">[238] The country's high rate of incarceration is largely due to sentencing and drug policies.<sup class="reference" id="cite_ref-SP_238-2">[238] <sup class="reference" id="cite_ref-HRW_243-0">[243]

Capital punishment is sanctioned in the United States for certain federal and military crimes, and used in thirty-three states.<sup class="reference" id="cite_ref-244">[244] No executions took place from 1967 to 1977, owing in part to a U.S. Supreme Court ruling striking down arbitrary imposition of the death penalty. In 1976, that Court ruled that, under appropriate circumstances, capital punishment may constitutionally be imposed; since the decision there have been more than 1,300 executions, a majority of these taking place in three states: Texas, Virginia, and Oklahoma.<sup class="reference" id="cite_ref-245">[245] Four state legislatures in the modern era have abolished the death penalty, though two of those laws (in New Mexico and Connecticut) were not retroactive. Additionally, state courts in Massachusetts and New York struck down death penalty statutes and their legislatures took no action in response. In 2010, the country had the fifth highest number of executions in the world, following China, Iran, North Korea, and Yemen.<sup class="reference" id="cite_ref-246">[246]

Demographics
Main articles: Demographics of the United States and AmericansLargest ancestry groups by county, 2000. The U.S. Census Bureau estimates the country's population now to be 314,924,000,<sup class="reference" id="cite_ref-POP_2-1">[2] including an estimated 11.2 million illegal immigrants.<sup class="reference" id="cite_ref-248">[248] The U.S. population almost quadrupled during the 20th century, from about 76 million in 1900.<sup class="reference" id="cite_ref-249">[249] The third most populous nation in the world, after China and India, the United States is the only major industrialized nation in which large population increases are projected.<sup class="reference" id="cite_ref-PRC_250-0">[250]

With a birth rate of 13 per 1,000, 35% below the world average, its population growth rate is positive at 0.9%, significantly higher than those of many developed nations.<sup class="reference" id="cite_ref-251">[251] In fiscal year 2011, over 1 million immigrants (most of whom entered through family reunification) were granted legal residence.<sup class="reference" id="cite_ref-LPR_252-0">[252] Mexico has been the leading source of new residents for over two decades; since 1998, China, India, and the Philippines have been in the top four sending countries every year.<sup class="reference" id="cite_ref-253">[253] 9 million Americans identify as lesbian, gay, bisexual or transgender, making up 4% of the population.<sup class="reference" id="cite_ref-254">[254]

The United States has a very diverse population—thirty-one ancestry groups have more than one million members.<sup class="reference" id="cite_ref-An2000_255-0">[255] White Americans are the largest racial group; German Americans, Irish Americans, and English Americans constitute three of the country's four largest ancestry groups.<sup class="reference" id="cite_ref-An2000_255-1">[255] Black Americans are the nation's largest racial minority and third largest ancestry group.<sup class="reference" id="cite_ref-An2000_255-2">[255] Asian Americans are the country's second largest racial minority; the two largest Asian American ethnic groups are Chinese Americans and Filipino Americans.<sup class="reference" id="cite_ref-An2000_255-3">[255]

In 2010, the U.S. population included an estimated 5.2 million people with some American Indian or Alaska Native ancestry (2.9 million exclusively of such ancestry) and 1.2 million with some native Hawaiian or Pacific island ancestry (0.5 million exclusively).<sup class="reference" id="cite_ref-Cen2010Race_256-0">[256] The census counted more than 19 million people of "Some Other Race" who were "unable to identify with any" of its five official race categories in 2010.<sup class="reference" id="cite_ref-Cen2010Race_256-1">[256]

The population growth of Hispanic and Latino Americans (the terms are officially interchangeable) is a major demographic trend. The 50.5 million Americans of Hispanic descent<sup class="reference" id="cite_ref-Cen2010Race_256-2">[256] are identified as sharing a distinct "ethnicity" by the Census Bureau; 64% of Hispanic Americans are of Mexican descent.<sup class="reference" id="cite_ref-CB2007_257-0">[257] Between 2000 and 2010, the country's Hispanic population increased 43% while the non-Hispanic population rose just 4.9%.<sup class="reference" id="cite_ref-Cen2010Summary_247-1">[247] Much of this growth is from immigration; as of 2007, 12.6% of the U.S. population was foreign-born, with 54% of that figure born in Latin America.<sup class="reference" id="cite_ref-258">[258]

Fertility is also a factor; as of 2010 the average Hispanic (of any race) woman gave birth to 2.35 children in her lifetime, compared to 1.97 for non-Hispanic black women and 1.79 for non-Hispanic white women (both below the replacement rate of 2.1).<sup class="reference" id="cite_ref-autogenerated1_259-0">[259] Minorities (as defined by the Census Bureau as all those beside non-Hispanic, non-multiracial whites) constituted 36.3% of the population in 2010,<sup class="reference" id="cite_ref-260">[260] and over 50% of children under age 1,<sup class="reference" id="cite_ref-261">[261] and are projected to constitute the majority by 2042.<sup class="reference" id="cite_ref-262">[262] This contradicts the report by the National Vital Statistics Reports, based on the US census data, which concludes that, 54% (2,162,406 out of 3,999,386 in 2010) of births were non-Hispanic white.<sup class="reference" id="cite_ref-autogenerated1_259-1">[259]

About 82% of Americans live in urban areas (including suburbs);<sup class="reference" id="cite_ref-WF_1-4">[1] about half of those reside in cities with populations over 50,000.<sup class="reference" id="cite_ref-263">[263] In 2008, 273 incorporated places had populations over 100,000, nine cities had more than 1 million residents, and four global cities had over 2 million (New York City, Los Angeles, Chicago, and Houston).<sup class="reference" id="cite_ref-PopEstBigCities_264-0">[264]

There are fifty-two metropolitan areas with populations greater than 1 million.<sup class="reference" id="cite_ref-PopEstMSA_265-0">[265] Of the fifty fastest-growing metro areas, forty-seven are in the West or South.<sup class="reference" id="cite_ref-266">[266] The metro areas of Dallas, Houston, Atlanta, and Phoenix all grew by more than a million people between 2000 and 2008.<sup class="reference" id="cite_ref-PopEstMSA_265-1">[265]

Language
Main article: Languages of the United StatesSee also: Language Spoken at Home and List of endangered languages in the United States English is the de facto national language. Although there is no official language at the federal level, some laws—such as U.S. naturalization requirements—standardize English. In 2010, about 230 million, or 80% of the population aged five years and older, spoke only English at home. Spanish, spoken by 12% of the population at home, is the second most common language and the most widely taught second language.<sup class="reference" id="cite_ref-Lang_269-1">[269] <sup class="reference" id="cite_ref-270">[270] Some Americans advocate making English the country's official language, as it is in at least twenty-eight states.<sup class="reference" id="cite_ref-ILW_5-1">[5] Both Hawaiian and English are official languages in Hawaii by state law.<sup class="reference" id="cite_ref-271">[271]

While neither has an official language, New Mexico has laws providing for the use of both English and Spanish, as Louisiana does for English and French.<sup class="reference" id="cite_ref-272">[272] Other states, such as California, mandate the publication of Spanish versions of certain government documents including court forms.<sup class="reference" id="cite_ref-273">[273] Many jurisdictions with large numbers of non-English speakers produce government materials, especially voting information, in the most commonly spoken languages in those jurisdictions.

Several insular territories grant official recognition to their native languages, along with English: Samoan and Chamorro are recognized by American Samoa and Guam, respectively; Carolinian and Chamorro are recognized by the Northern Mariana Islands; Spanish is an official language of Puerto Rico and is more widely spoken than English there.

Religion
A pie chart of religious groups in the US (2007).Main article: Religion in the United StatesSee also: History of religion in the United States, Freedom of religion in the United States, Separation of church and state in the United States, and List of religious movements that began in the United StatesThe United States is officially a secular nation; the First Amendment of the U.S. Constitution guarantees the free exercise of religion and forbids the establishment of any religious governance. In a 2002 study, 59% of Americans said that religion played a "very important role in their lives", a far higher figure than that of any other wealthy nation.<sup class="reference" id="cite_ref-274">[274] According to a 2007 survey, 78.4% of adults identified themselves as Christian,<sup class="reference" id="cite_ref-Pew_275-0">[275] down from 86.4% in 1990.<sup class="reference" id="cite_ref-ARIS_276-0">[276]

Protestant denominations accounted for 51.3%, while Roman Catholicism, at 23.9%, was the largest individual denomination.<sup class="reference" id="cite_ref-Pew_275-1">[275] The total reporting non-Christian religions in 2007 was 4.7%, up from 3.3% in 1990.<sup class="reference" id="cite_ref-ARIS_276-1">[276] Other religions include Judaism (1.7%), Buddhism (0.7%), Islam (0.6%), Hinduism (0.4%), and Unitarian Universalism (0.3%).<sup class="reference" id="cite_ref-Pew_275-2">[275] The survey also reported that 16.1% of Americans described themselves as agnostic, atheist, or simply having no religion, up from 8.2% in 1990.<sup class="reference" id="cite_ref-Pew_275-3">[275] <sup class="reference" id="cite_ref-ARIS_276-2">[276]

There are also Baha'i, Wiccan, Druid, Jain, Native American, humanist and deist communities.<sup class="reference" id="cite_ref-277">[277] Doubt about the existence of a god or gods is growing rapidly among Americans under 30.<sup class="reference" id="cite_ref-278">[278] Polls show that overall American confidence in organized religion is declining,<sup class="reference" id="cite_ref-279">[279] and that younger Americans in particular are becoming increasingly irreligious.<sup class="reference" id="cite_ref-280">[280]

Family structure
Main article: Family structure in the United StatesIn 2007, 58% of Americans age 18 and over were married, 6% were widowed, 10% were divorced, and 25% had never been married.<sup class="reference" id="cite_ref-281">[281] Women now mostly work outside the home and receive a majority of bachelor's degrees.<sup class="reference" id="cite_ref-282">[282]

Same-sex marriage is a contentious issue. Some states permit civil unions or domestic partnerships in lieu of marriage. Since 2003, several states have legalized gay marriage as the result of judicial or legislative action. Meanwhile, the federal government and a majority of states define marriage as between a man and a woman and/or explicitly prohibit same-sex marriage. Public opinion on the issue has shifted from general opposition in the 1990s to a statistical deadlock, to a majority in support.<sup class="reference" id="cite_ref-283">[283]

The U.S. teenage pregnancy rate, 79.8 per 1,000 women, is the highest among OECD nations.<sup class="reference" id="cite_ref-284">[284] Abortion policy was left to the states until the Supreme Court legalized the practice in 1973. The issue remains highly controversial, with public opinion closely divided for many years. Many states ban public funding of the procedure and restrict late-term abortions, require parental notification for minors, and mandate a waiting period. While the abortion rate is falling, the abortion ratio of 241 per 1,000 live births and abortion rate of 15 per 1,000 women aged 15–44 remain higher than those of most Western nations.<sup class="reference" id="cite_ref-285">[285]

Culture
Main article: Culture of the United StatesSee also: Social class in the United StatesThe Statue of Liberty in New York City is a symbol of both the US and ideals of freedom, democracy, and opportunity.<sup class="reference" id="cite_ref-286">[286] The United States is a multicultural nation, home to a wide variety of ethnic groups, traditions, and values.<sup class="reference" id="cite_ref-DD_6-1">[6] <sup class="reference" id="cite_ref-Society_in_Focus_287-0">[287] Aside from the now small Native American and Native Hawaiian populations, nearly all Americans or their ancestors immigrated within the past five centuries.<sup class="reference" id="cite_ref-288">[288] Mainstream American culture is a Western culture largely derived from the traditions of European immigrants with influences from many other sources, such as traditions brought by slaves from Africa.<sup class="reference" id="cite_ref-DD_6-2">[6] <sup class="reference" id="cite_ref-289">[289] More recent immigration from Asia and especially Latin America has added to a cultural mix that has been described as both a homogenizing melting pot, and a heterogeneous salad bowl in which immigrants and their descendants retain distinctive cultural characteristics.<sup class="reference" id="cite_ref-DD_6-3">[6]

American culture is considered the most individualistic in the world.<sup class="reference" id="cite_ref-290">[290] The American Dream, or the perception that Americans enjoy high social mobility, plays a key role in attracting immigrants.<sup class="reference" id="cite_ref-291">[291] While the mainstream culture holds that the United States is a classless society,<sup class="reference" id="cite_ref-292">[292] scholars identify significant differences between the country's social classes, affecting socialization, language, and values.<sup class="reference" id="cite_ref-293">[293]

The American middle and professional class has initiated many contemporary social trends such as modern feminism, environmentalism, and multiculturalism.<sup class="reference" id="cite_ref-294">[294] Americans' self-images, social viewpoints, and cultural expectations are associated with their occupations to an unusually close degree.<sup class="reference" id="cite_ref-295">[295] While Americans tend greatly to value socioeconomic achievement, being ordinary or average is generally seen as a positive attribute.<sup class="reference" id="cite_ref-296">[296]

Popular media
Main articles: Cinema of the United States, Television in the United States, and Music of the United StatesThe Hollywood Sign in Los Angeles, California.The world's first commercial motion picture exhibition was given in New York City in 1894, using Thomas Edison's Kinetoscope. The next year saw the first commercial screening of a projected film, also in New York, and the United States was in the forefront of sound film's development in the following decades. Since the early 20th century, the U.S. film industry has largely been based in and around Hollywood, California.

Director D. W. Griffith was central to the development of film grammar and Orson Welles's Citizen Kane (1941) is frequently cited as the greatest film of all time.<sup class="reference" id="cite_ref-297">[297] American screen actors like John Wayne and Marilyn Monroe have become iconic figures, while producer/entrepreneur Walt Disney was a leader in both animated film and movie merchandising. The major film studios of Hollywood have produced the most commercially successful movies in history, such as Star Wars (1977) and Titanic (1997), and the products of Hollywood today dominate the global film industry.<sup class="reference" id="cite_ref-298">[298]

Americans are the heaviest television viewers in the world,<sup class="reference" id="cite_ref-299">[299] and the average viewing time continues to rise, reaching five hours a day in 2006.<sup class="reference" id="cite_ref-300">[300] The four major broadcast networks are all commercial entities. Americans listen to radio programming, also largely commercialized, on average just over two-and-a-half hours a day.<sup class="reference" id="cite_ref-301">[301] Aside from web portals and search engines, the most popular websites are Facebook, YouTube, Wikipedia, Blogger, eBay, and Craigslist.<sup class="reference" id="cite_ref-alexa-topsitesus_302-0">[302]

The rhythmic and lyrical styles of African-American music have deeply influenced American music at large, distinguishing it from European traditions. Elements from folk idioms such as the blues and what is now known as old-time music were adopted and transformed into popular genres with global audiences. Jazz was developed by innovators such as Louis Armstrong and Duke Ellington early in the 20th century. Country music developed in the 1920s, and rhythm and blues in the 1940s.<sup class="reference" id="cite_ref-autogenerated2001_303-0">[303]

Elvis Presley and Chuck Berry were among the mid-1950s pioneers of rock and roll. In the 1960s, Bob Dylan emerged from the folk revival to become one of America's most celebrated songwriters and James Brown led the development of funk. More recent American creations include hip hop and house music. American pop stars such as Presley, Michael Jackson, and Madonna have become global celebrities.<sup class="reference" id="cite_ref-autogenerated2001_303-1">[303]

Literature, philosophy, and the arts
Main articles: American literature, American philosophy, Visual art of the United States, and American classical musicMark Twain, famous American author and humourist.In the 18th and early 19th centuries, American art and literature took most of its cues from Europe. Writers such as Nathaniel Hawthorne, Edgar Allan Poe, and Henry David Thoreau established a distinctive American literary voice by the middle of the 19th century. Mark Twain and poet Walt Whitman were major figures in the century's second half; Emily Dickinson, virtually unknown during her lifetime, is now recognized as an essential American poet.<sup class="reference" id="cite_ref-304">[304] A work seen as capturing fundamental aspects of the national experience and character—such as Herman Melville's Moby-Dick (1851), Twain's The Adventures of Huckleberry Finn (1885), and F. Scott Fitzgerald's The Great Gatsby (1925)—may be dubbed the "Great American Novel".<sup class="reference" id="cite_ref-305">[305]

Eleven U.S. citizens have won the Nobel Prize in Literature, most recently Toni Morrison in 1993. William Faulkner and Ernest Hemingway are often named among the most influential writers of the 20th century.<sup class="reference" id="cite_ref-306">[306] Popular literary genres such as the Western and hardboiled crime fiction developed in the United States. The Beat Generation writers opened up new literary approaches, as have postmodernist authors such as John Barth, Thomas Pynchon, and Don DeLillo.

The transcendentalists, led by Thoreau and Ralph Waldo Emerson, established the first major American philosophical movement. After the Civil War, Charles Sanders Peirce and then William James and John Dewey were leaders in the development of pragmatism. In the 20th century, the work of W. V. O. Quine and Richard Rorty, and later Noam Chomsky, brought analytic philosophy to the fore of American philosophical academia. John Rawls and Robert Nozick led a revival of political philosophy.

In the visual arts, the Hudson River School was a mid-19th-century movement in the tradition of European naturalism. The realist paintings of Thomas Eakins are now widely celebrated. The 1913 Armory Show in New York City, an exhibition of European modernist art, shocked the public and transformed the U.S. art scene.<sup class="reference" id="cite_ref-307">[307] Georgia O'Keeffe, Marsden Hartley, and others experimented with new, individualistic styles. Major artistic movements such as the abstract expressionism of Jackson Pollock and Willem de Kooning and the pop art of Andy Warhol and Roy Lichtenstein developed largely in the United States. The tide of modernism and then postmodernism has brought fame to American architects such as Frank Lloyd Wright, Philip Johnson, and Frank Gehry. Times Square in New York City, part of the Broadway theater district.One of the first major promoters of American theater was impresario P. T. Barnum, who began operating a lower Manhattan entertainment complex in 1841. The team of Harrigan and Hart produced a series of popular musical comedies in New York starting in the late 1870s. In the 20th century, the modern musical form emerged on Broadway; the songs of musical theater composers such as Irving Berlin, Cole Porter, and Stephen Sondheim have become pop standards. Playwright Eugene O'Neill won the Nobel literature prize in 1936; other acclaimed U.S. dramatists include multiple Pulitzer Prize winners Tennessee Williams, Edward Albee, and August Wilson.

Though little known at the time, Charles Ives's work of the 1910s established him as the first major U.S. composer in the classical tradition, while experimentalists such as Henry Cowell and John Cage created a distinctive American approach to classical composition. Aaron Copland and George Gershwin developed a new synthesis of popular and classical music. Choreographers Isadora Duncan and Martha Graham helped create modern dance, while George Balanchine and Jerome Robbins were leaders in 20th-century ballet. Americans have long been important in the modern artistic medium of photography, with major photographers including Alfred Stieglitz, Edward Steichen, and Ansel Adams. The newspaper comic strip and the comic book are both U.S. innovations. Superman, the quintessential comic book superhero, has become an American icon.<sup class="reference" id="cite_ref-308">[308]

Food
Main article: Cuisine of the United StatesMainstream American cuisine is similar to that in other Western countries. Wheat is the primary cereal grain. Traditional American cuisine uses indigenous ingredients, such as turkey, venison, potatoes, sweet potatoes, corn, squash, and maple syrup, which were consumed by Native Americans and early European settlers.

Slow-cooked pork and beef barbecue, crab cakes, potato chips, and chocolate chip cookies are distinctively American foods. Soul food, developed by African slaves, is popular around the South and among many African Americans elsewhere. Syncretic cuisines such as Louisiana creole, Cajun, and Tex-Mex are regionally important.

Characteristic dishes such as apple pie, fried chicken, pizza, hamburgers, and hot dogs derive from the recipes of various immigrants. French fries, Mexican dishes such as burritos and tacos, and pasta dishes freely adapted from Italian sources are widely consumed.<sup class="reference" id="cite_ref-IFT_309-0">[309] Americans generally prefer coffee to tea. Marketing by U.S. industries is largely responsible for making orange juice and milk ubiquitous breakfast beverages.<sup class="reference" id="cite_ref-310">[310]

The American fast food industry, the world's largest, pioneered the drive-through format in the 1930s. Fast food consumption has sparked health concerns. During the 1980s and 1990s, Americans' caloric intake rose 24%;<sup class="reference" id="cite_ref-IFT_309-1">[309] frequent dining at fast food outlets is associated with what public health officials call the American "obesity epidemic".<sup class="reference" id="cite_ref-311">[311] Highly sweetened soft drinks are widely popular, and sugared beverages account for 9% of American caloric intake.<sup class="reference" id="cite_ref-312">[312]

Sports
Main article: Sports in the United StatesSwimmer Michael Phelps is the most decorated Olympic athlete of all time.Baseball has been regarded as the national sport since the late 19th century, while American football is now by several measures the most popular spectator sport.<sup class="reference" id="cite_ref-313">[313] Basketball and ice hockey are the country's next two leading professional team sports. College football and basketball attract large audiences. Boxing and horse racing were once the most watched individual sports,<sup class="reference" id="cite_ref-314">[314] but they have been eclipsed by golf and auto racing, particularly NASCAR. Soccer continues to grow in the United States, as it is played widely at the youth and amateur levels. Tennis and many outdoor sports are popular as well.

While most major U.S. sports have evolved out of European practices, basketball, volleyball, skateboarding, snowboarding, and cheerleading are American inventions. Lacrosse and surfing arose from Native American and Native Hawaiian activities that predate Western contact. Eight Olympic Games have taken place in the United States. The United States has won 2,301 medals at the Summer Olympic Games, more than any other country,<sup class="reference" id="cite_ref-315">[315] and 253 in the Winter Olympic Games, the second most by 2006.<sup class="reference" id="cite_ref-316">[316]

Measurement systems
Main articles: United States customary units and Metrication in the United StatesAlthough the United States authorized the metric system in 1866 and was one of the original 17 signatory nations to the Metre Convention of 1875, the nation primarily relies on the United States customary units, very similar to the British imperial units system and also derived from the historical English units system, employing feet, miles, and degrees Fahrenheit. Distinctive units include the U.S. gallon and U.S. pint volume measurements. According to the CIA Factbook, the United States is one of three countries that has not adopted the International System of Units (SI) metric system as their official system of weights and measures. However, SI predominates in science, medicine, technology, and international commerce.<sup class="reference" id="cite_ref-317">[317]